The present invention relates generally to an apparatus and method for mounting a bearing. More particularly, in one embodiment, the present invention defines an apparatus for mounting a ceramic inner race of a bearing for a gas turbine engine. Although the present invention was developed for use in a gas turbine engine, certain applications may be outside of this field.
There is a continuing need to improve the efficiency and simplify the construction of the gas turbine engine. One approach is the development of materials for bearings that do not require lubrication, or that use lubrication systems which are simplified. Ceramic materials, particularly silicon nitride, are candidate bearing materials for such advanced gas turbine engines. Other materials, including variants of ceramics and metals, will doubtless be proposed in the future.
There are problems, however, in the use of ceramics when the ceramic material is under tension. Ceramics are typically characterized with low fracture toughness, meaning that imperfections in the material result in the bearing being susceptible to tensile failure. Other materials may have similar problems, or may be better suited to bearing applications if the degree of tension in the material can be controlled.
Various inventions have been proposed for providing bearings within gas turbine engines. Examples of bearings can be found in the following U.S. Pat. No. 4,792,244 issued to Yamashita et al; U.S. Pat. No. 5,176,456 issued to Takebayashi; U.S. Pat. No. 5,575,571 to Takebayashi et al.; U.S. Pat. No. 4,968,158 issued to Atkinson et al.; U.S. Pat. No. 5,306,565 issued to Corbin et al; U.S. Pat. No. 4,997,296 to Narita et al.; U.S. Pat. No. 5,197,808 to Takata; U.S. Pat. No. 5,568,985 to Schutte; U.S. Pat. No. 5,600,867 to Niwa et al. al.; U.S. Pat. No. 5,197,808 to Takata; U.S. Pat. No. 5,568,985 to Schutte; U.S. Pat. No. 5,600,867 to Niwa et al.
Even with the variety of earlier designs, there remains a need for an improved apparatus and method for mounting the inner race of a bearing. The present invention satisfies this need in a novel and unobvious way.